Anaemia in Cats with Chronic Kidney Disease: Causes, Signs and Treatment

Chronic kidney disease (CKD) is one of the most common long-term conditions affecting older cats. As kidney function declines, it can affect hydration, appetite, blood pressure, body weight and several important processes elsewhere in the body.

One complication that can develop in cats with CKD is non-regenerative anaemia. This means that the number of circulating red blood cells is reduced and the bone marrow is not producing enough new red blood cells to compensate.

Anaemia can contribute to tiredness, weakness, reduced appetite and a poorer quality of life, particularly when it becomes more severe.

Why Can Chronic Kidney Disease Cause Anaemia?

Healthy kidneys do much more than filter waste products from the blood. They are also involved in regulating red blood cell production.

One of the important hormones involved is erythropoietin, often shortened to EPO. Erythropoietin signals the bone marrow to produce red blood cells.

As chronic kidney disease progresses, the kidneys may become less able to support normal erythropoietin production. This can contribute to reduced red blood cell production and the development of non-regenerative anaemia.

Anaemia in a cat with CKD is not always caused by kidney disease alone. Other possible contributors can include inflammation, iron deficiency, gastrointestinal blood loss and other concurrent illnesses. These may need to be investigated if anaemia develops or does not respond as expected.

How Is Anaemia Diagnosed?

Anaemia is identified using a blood test. Measurements such as the packed cell volume (PCV), haematocrit (HCT), haemoglobin concentration and red blood cell count help determine whether a cat is anaemic and how significant the anaemia is.

Further blood tests may help determine whether the anaemia is regenerative or non-regenerative and whether another underlying condition could be contributing.

Your veterinary surgeon may also consider the cat's kidney values, hydration status, blood pressure, urine results, iron status and overall clinical condition when deciding how significant the anaemia is and whether treatment is required.

How Is Anaemia Associated with CKD Managed?

Treatment depends on the severity of the anaemia, the stage of kidney disease, the cat's clinical signs and whether any additional causes of anaemia are identified.

Management may involve several different approaches, including:

• Optimising the overall management of chronic kidney disease
• Investigating and treating underlying blood loss where present
• Assessing and addressing iron deficiency where appropriate
• Supporting hydration, nutrition and appetite
• Monitoring red blood cell levels over time
• Blood transfusion in some cats with severe or clinically significant anaemia
• Prescription treatment to stimulate red blood cell production where considered appropriate by the veterinary surgeon

The most appropriate approach varies considerably between cats. Treatment decisions should therefore be based on the individual patient rather than the blood test result alone.

What Is Molidustat?

Molidustat is an active substance belonging to a group known as hypoxia-inducible factor prolyl hydroxylase inhibitors, usually shortened to HIF-PH inhibitors.

Molidustat works by stabilising hypoxia-inducible factor within the body. This increases the production of endogenous erythropoietin, which in turn stimulates the bone marrow to produce more red blood cells.

Molidustat is an active substance authorised for veterinary use in cats for the treatment of non-regenerative anaemia associated with chronic kidney disease.

It is a prescription treatment, so whether it is appropriate for an individual cat is a decision for the prescribing veterinary surgeon following assessment of the cat's clinical condition and blood test results.

Monitoring Anaemia During Treatment

Cats being treated for CKD-associated anaemia require ongoing veterinary monitoring. The frequency of blood testing depends on the individual cat, the severity of the anaemia, the treatment being used and the response to therapy.

Monitoring commonly includes packed cell volume or haematocrit measurements alongside assessment of the cat's kidney disease and general clinical condition.

If the red blood cell response is not as expected, the veterinary surgeon may investigate other possible contributors to anaemia, such as iron deficiency, inflammation or blood loss.

HIF-PH inhibitors have also been associated with thromboembolic disease, so the individual patient's health and any factors that may increase thromboembolic risk should be considered by the prescribing veterinary surgeon.

Managing the Underlying Kidney Disease

Treating anaemia is only one part of caring for a cat with chronic kidney disease. CKD management is usually tailored to the individual cat and may include:

• Appropriate renal nutrition
• Maintaining hydration
• Blood pressure monitoring and management
• Management of excessive urinary protein loss where present
• Phosphate monitoring and control
• Management of nausea or reduced appetite
• Regular body weight and muscle condition monitoring
• Repeat blood and urine testing to monitor disease progression

Not every cat requires every intervention. Treatment plans often change over time as kidney disease progresses or as new clinical problems develop.

When Should I Contact My Vet?

Cats with chronic kidney disease should have regular veterinary monitoring even when they appear stable.

Contact your veterinary practice if you notice a significant change in your cat's appetite, energy levels, breathing, mobility, drinking or urination, or if the gums appear unusually pale.

Sudden weakness, collapse, difficulty breathing or profound lethargy should be treated as urgent signs and assessed promptly by a veterinary surgeon.

Frequently Asked Questions